Photodetectors Integrated into Thin-Film Transistor Backplanes

Abstract

An electronic device includes a stack, and the stack includes a substrate, and a multi-layer structure deposited on the substrate and including a set of TFTs. The electronic device further includes a photodetector attached to the multi-layer structure and including an organic photosensitive material. The organic photosensitive material is electrically connected to a TFT in the set of TFTs. Another electronic device includes a stack, and the stack includes a substrate, and a multi-layer structure deposited on the substrate. The multi-layer structure includes a first set of layers including a set of TFTs, and a second set of layers including a PIN diode. The PIN diode is configured to operate as a photodetector and receive at least one wavelength of electromagnetic radiation, and is electrically connected to a TFT in the set of TFTs.

What is claimed is: 
     
         1 . An electronic device, comprising:
 a stack, including,
 a substrate; and 
 a multi-layer structure deposited on the substrate and including a set of thin-film transistors (TFTs); and 
   a photodetector attached to the multi-layer structure and including an organic photosensitive material; wherein:   the organic photosensitive material is electrically connected to a transistor in the set of TFTs.   
     
     
         2 . The electronic device of  claim 1 , further comprising:
 a housing defining at least part of an interior volume and an opening into the interior volume;   a cover mounted to the housing to cover the opening and further define the interior volume; and   a display mounted within the interior volume and viewable through the cover; wherein:   the stack is attached to a side of the display opposite the cover; and   the photodetector is positioned to receive light through the display.   
     
     
         3 . The electronic device of  claim 2 , further comprising at least one of a lens, an optical waveguide, an optical polarizer, or an optical film, positioned between the display and the stack. 
     
     
         4 . The electronic device of  claim 2 , wherein:
 the multi-layer structure including the set of TFTs is a first multi-layer structure including a first set of TFTs; and   the display includes:
 a second substrate; 
 a second multi-layer structure deposited on the second substrate and including a second set of TFTs; and 
 an organic light-emitting material deposited on the second multi-layer structure and electrically connected to a set of drive transistors in the second set of TFTs. 
   
     
     
         5 . The electronic device of  claim 2 , wherein the display comprises a bottom-emission liquid crystal display (LCD). 
     
     
         6 . The electronic device of  claim 1 , wherein the organic photosensitive material forms a planarization layer of the multi-layer structure. 
     
     
         7 . The electronic device of  claim 6 , wherein the planarization layer is a first planarization layer, the electronic device further comprising:
 a second planarization layer between the first planarization layer and the set of TFTs.   
     
     
         8 . The electronic device of  claim 6 , wherein:
 the organic photosensitive material forms at least a first planarization layer and a second planarization layer of the multi-layer structure; and   the electronic device further comprises an electrode positioned between the first planarization layer and the second planarization layer and electrically connected to the transistor.   
     
     
         9 . The electronic device of  claim 1 , wherein the photodetector comprises an organic avalanche photodiode (O-APD). 
     
     
         10 . The electronic device of  claim 1 , wherein the multi-layer structure comprises a Low-Temperature Polycrystalline Oxide (LTPO) organic light-emitting diode (OLED) display backplane. 
     
     
         11 . An electronic device, comprising:
 a housing defining part of an interior volume and an opening to the interior volume;   a cover mounted to the housing to cover the opening and further define the interior volume; and   a display stack mounted within the interior volume and viewable through the cover, the display stack including:
 a thin-film transistor (TFT) display backplane formed on a flexible substrate; 
 an array of light-emitting pixels, disposed between the cover and the TFT display backplane and electrically connected to the TFT display backplane; and 
 a photodetector formed in the TFT display backplane. 
   
     
     
         12 . The electronic device of  claim 11 , wherein:
 the photodetector is positioned between light-emitting pixels of the array of light-emitting pixels; and   the photodetector is electrically connected to the TFT display backplane.   
     
     
         13 . The electronic device of  claim 11 , wherein:
 the photodetector is stacked under a light-emitting pixel of the array of light-emitting pixels; and   the photodetector is electrically connected to the TFT display backplane.   
     
     
         14 . An electronic device, comprising:
 a stack, including,
 a substrate; and 
 a multi-layer structure deposited on the substrate and including:
 a first set of layers including a set of thin-film transistors (TFTs); and 
 a second set of layers including a PIN diode; wherein: 
 
   the PIN diode is configured to operate as a photodetector and receive at least one wavelength of electromagnetic radiation; and   the PIN diode is electrically connected to at least one TFT in the set of TFTs.   
     
     
         15 . The electronic device of  claim 14 , wherein:
 the first set of layers and the second set of layers share an electrical contact layer; and   each of the PIN diode and the at least one TFT is connected to a respective electrical contact in the electrical contact layer.   
     
     
         16 . The electronic device of  claim 14 , wherein:
 the first set of layers includes a TFT oxide layer; and   the at least one TFT has a gate formed in the TFT oxide layer.   
     
     
         17 . The electronic device of  claim 16 , wherein the first set of layers further includes a silicon-based TFT. 
     
     
         18 . The electronic device of  claim 16 , wherein the PIN diode is silicon-based. 
     
     
         19 . The electronic device of  claim 16 , wherein:
 the PIN diode is electrically connected to an electrode comprising titanium; and   the titanium operates as a hydrogen getter.   
     
     
         20 . The electronic device of  claim 14 , wherein the PIN diode is electrically connected to an electrode that extends over the at least one TFT.